This disclosure relates to an optoelectronic circuit and more specifically to a combination of microwave and photonic components for a compact, self contained Mach-Zehnder interferometer (MZI) modulator.
Modulation of an optical signal at microwave frequencies, typically above 10 GHz, requires external modulation of a laser source to prevent unintentional modulation of the laser frequency (e.g. chirping). Towards this end, a Mach-Zehnder interferometer structure is often employed to create an optical phase and/or amplitude modulator. One or both arms of the Mach-Zehnder interferometer contains electrodes to permit phase modulation of an optical signal via the electro-optic effect. These electrodes require a drive amplifier to supply adequate electric field to produce the electro-optic effect. The amplifier requires sufficient bandwidth and output capability to drive the reactive load presented by the Mach-Zehnder electrodes.
Early electro-optic (EO) modulators required a large external power amplifier to provide hundreds of volts to produce the electro-optic effect. Recent devices have the modest drive requirement of 8-12 volts, but still require an external RF power amplifier to operate. Advances in polymer technology have allowed for the development of materials with large EO figures of merit, resulting in low V xcfx80 numbers.
An embodiment of the invention is an integrated optoelectronic circuit comprising a first flexible dielectric substrate having a first surface and an opposing second surface. A polymer electro-optic waveguide is positioned on or embedded within the flexible dielectric substrate and receptive of an optical signal. A ground electrode is positioned along the electro-optic waveguide and a signal electrode is positioned along the electro-optic waveguide opposite the ground electrode. A first microchip including a first modulator receptive of a modulating signal is positioned on the first flexible dielectric substrate. A first patterned metallization layer is positioned on the first flexible dielectric substrate coupling the ground electrode to the modulator. A second flexible dielectric substrate having a first surface and an opposing second surface is positioned along the first flexible dielectric substrate. A second patterned metallization layer is positioned on the second flexible dielectric substrate coupling the signal electrode to the modulator.
Another embodiment is a method of fabricating an integrated optoelectronic circuit, the method comprising positioning a microchip, including a modulator, on a first flexible dielectric substrate; positioning a polymer electro-optic waveguide on or within the first flexible dielectric substrate; positioning a ground electrode along the electro-optic waveguide; positioning a signal electrode along the electro-optic waveguide opposite the ground electrode; applying a first patterned metallization layer to the first flexible dielectric substrate thereby coupling the ground electrode and the modulator; positioning a second flexible dielectric substrate along the first flexible dielectric substrate; providing a plurality of via openings in the first and second flexible dielectric substrates; and applying a second patterned metallization layer to the second flexible dielectric substrate thereby coupling the signal electrode and the modulator.